V. — Caseoses, Casein Dtspeptone, and Casein Peptone. By 

 R. PI. Chittenden. 



In a previous paper on " Casein and its Primary Cleavage Pro- 

 ducts,"* the writer expressed the intention of continuing the study of 

 the caseoses formed in pepsin digestion, and also of studying pure 

 casein peptone and the so-called casein dyspeptone. In the fulfillment 

 of this intention, experiments upon these subjects have been carried 

 on in this laboratory during the past two years, with the aid of sev- 

 eral co-workers, and the results are here presented collectively. 



I. — Casein Dyspeptone ; — from experiments by L. ^4. Conner, Ph. B., axiA 



C. A. Tuttle, Pli.B. 



When casein is exposed to the action of pepsin-hydrochloric acid 

 at 40° C, or even at ordinary temperatures,-it is decomposed, as is 

 well known, into soluble caseoses and peptone. In every such diges- 

 tion, however, there always remains a certain amount of an insoluble 

 pasty, grayish white substance, which apparently is not susceptible 

 to the further action of gastric juice, no matter how long continued. 

 This insoluble substance, which is noticeable to a greater or less extent 

 in the pepsin digestion of all proteids, but particularly so with casein, 

 and which received from Meissner the name of dyspeptone, was 

 examined somewhat carefully by Lubavin in 1876,f who described 

 some of its properties. lie considered this casein dyspeptone as a 

 mixture of two distinct bodies, separable from each other by the 

 action of sodium carbonate. Substance A^ that portion of the dys- 

 peptone soluble in sodium carbonate, was described by Lubavin as a 

 body containing 4-6 per cent, of phosphorus, 13*3 per cent, of nitro- 

 gen, 48*5 per cent, of carbon and no sulphur, corresponding to the 

 formula C^^H^^N^POj^. Substance J5, insoluble in sodium carbonate, 

 was slowly soluble in sodium hydroxide, contained sulphur, but only 

 a small trace of phosphorus and evidently contained more or less 



* Chittenden and Painter. Studies from Laboratory of Physiological Chemistry 

 Yale University, vol. ii., p. 156. 



f Hoppe-Seyler. Med. Chem. Untersuchungeu, p. 463. 



